Smoke in the battery room

Smoke was observed   in the battery room of a vessel alongside. The fire detection alarm went off on the bridge. A visual check at the scene confirmed visible smoke. The general fire alarm was promptly raised, initiating an organized muster and emergency response.

The event was brought under control by the onboard firefighting teams. Ventilation to the area was controlled and the relevant electrical circuits were isolated. The source of the smoke was identified as a set of overheated Nickel-Cadmium (Ni-Cd) batteries used for one of the UPS’s (Uninterruptible Power Supplies) for the vessel’s DP system. All damaged batteries were manually disconnected, removed and submerged in galvanized containers filled with water for cooling and containment.

The batteries involved were manufactured in 2021. The batteries of this brand and type had been specifically selected for their robustness and resilience against higher ambient temperatures. The affected cabinet contained 32 Ni-Cd batteries configured across 4 shelves. Evidence of localized heating and off-gassing was observed without open flame. Closer investigation or investigation after the event showed chipping of plastic casings, likely from transport or installation.

The incident was contained without any injury or escalation. The on-board fire-fighting teams involved were medically checked as a precaution and returned to full duty later that evening.

• Battery overheating and gas accumulation: One Ni-Cd battery overheated, resulting in a chain reaction of gassing and smouldering across multiple units. The root cause could not be definitively identified but may relate to internal damage (chipped casings) during earlier transport or installation.
• Battery cabinet accessibility: The original bolt-nut connection of the bars securing the batteries in the cabinet made rapid disconnection and removal of batteries cumbersome during the emergency, given that the firefighting crew was wearing full fire-fighting PPE.
• Gaps in documentation: The UPS unit connected to the batteries, had been replaced under warranty during the vessels’ initial commissioning phase. Although the complete DP system including the UPS had been successfully tested after the replacement, detailed replacement records or an individual commissioning report of the replaced unit were incomplete or unavailable.
• Inventory of all batteries on board: While the fire response was effective, there was confusion regarding the type of batteries involved. Initial reports incorrectly identified the fire as involving Lithium-Ion batteries. This uncertainty highlighted the need for a centralised and accessible overview of all batteries on board, including their types and locations.

• Quick detection and confirmation: The fire detection system worked as intended, allowing swift verification and escalation of the response.
• Swift coordinated response: The onboard emergency teams acted decisively and calmly under pressure, with roles and responsibilities clearly understood.